(1) Field of the Invention
The present invention relates to fluidics. More specifically, the present invention relates to fluid amplifiers and particularly to proportional fluidic devices which achieve control of a stream of a first fluid by means of regulating the flow of a second fluid. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
(2) Description of the Prior Art
As noted above, the present invention relates to the field of fluidics. Fluidics may be defined as the technology relating to the control of jets of high velocity fluid. In recent years, this field has attracted considerable attention and those skilled in the art have become aware of the numerous attributes of fluid devices such as switches and amplifiers.
Among the aforementioned attributes, the lack of moving parts in the fluidic control device has made such devices particularly attractive for control purposes. Thus, for example, it has long been desired to utilize a fluidic amplifier disposed between a source of pressurized fluid and a fluid consuming load to regulate the quantity and/or pressure of fluid delivered to the load. Such apparatus, if practical, could be employed to control the delivery of fuel to the engine of a vehicle.
The use of fluidic devices, and particularly in fuel control applications, has been hampered by several factors. Firstly, and perhaps most importantly, prior art fluid amplifiers have inherently had low gain and exceptionally low signal-to-noise ratio.
In order to conserve the power or operating stream fluid, particularly in cases where the power stream was being consumed by the load, it has been considered desirable to employ a second fluid for power stream control purposes. Attempts to utilize dissimilar fluids in a single device have previously resulted in non-linear operation due in part to the creation of turbulence and the fact that prior art devices have, as noted above, had low signal-to-noise ratio and low gain.
The low signal-to-noise ratio and, in addition thereto, non-linear response of prior art fluidic devices is in part a consequence of the fact that most of such prior devices operate on a momentum interaction principle. Thus, conventional prior art fluid amplifiers operate mainly on mechanical principles whereby the pressure of a control stream oriented substantially transversely to the power stream simply pushes the power stream in the desired direction with the amount of power stream deflection being some function of the momentum of the control stream. This momentum interaction causes flow disruption along the boundary of the power stream and thus promotes turbulent mixing with the surrounding medium. This turbulence, in turn, generates noise which results in non-linearity.